High performance wafer scale flexible InP double heterogeneous bipolar transistors

Abstract

This letter reports on the first demonstration of wafer scale flexible InP double heterogeneous bipolar transistors (DHBTs) with record cut-off frequency (f T) and maximum oscillation frequency (f MAX). The as-fabricated DHBTs on 3-inch InP bulk substrate are separated by epitaxial layer lift-off, followed by adhesive bonding onto flexible substrate. Radio frequency measurements reveal that the InP DHBTs on flexible substrate exhibit a f T of 337 GHz and f MAX of 485 GHz, representing the highest f T and f MAX ever reported in flexible electronics. Moreover, InP DHBTs on flexible substrate have good consistency and the functional transistor yield is more than 73%. The results provide ways to accelerate the time for flexible electronics toward future applications working at multi-gigahertz range.